Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$83.87	13.566%	$95.2478	$95.25	$95.25	$95.20
Purchase #2	$238.50	6.511%	$254.0287	$254.03	$254.05	$254.00
Purchase #3	$223.90	4.241%	$233.3956	$233.40	$233.40	$233.40
Purchase #4	$168.28	5.559%	$177.6347	$177.63	$177.65	$177.60
Purchase #5	$139.57	8.505%	$151.4404	$151.44	$151.45	$151.40
Purchase #6	$35.89	3.810%	$37.2574	$37.26	$37.25	$37.30
Purchase #7	$72.95	11.858%	$81.6004	$81.60	$81.60	$81.60
7 purchase totals =	$962.96		$1,030.6050	$1,030.61	$1,030.65	$1,030.50